Report:

Sinus tachycardia 106/min

Right atrial abnormality (RAA)

Second degree AV block, Möbitz 1

Up to 0.48” PR Intervals

Junctional escape beat (third last QRS)

LVH with ST/T changes

Comment:

The 4:3 and 5:4 Wenckebach cycles seen from beginning to end are atypical in that the last conducted cycle before the pause is not the shortest: the distal chamber fails to accelerate. Most Wenckebach cycles seen in clinical practice, especially long ones, are ‘atypical’ in some way. Prolongation of the last one or two cycles or failure of decremental increase in AV conduction are the commonest reasons for this.

The third last QRS has a much shorter PR interval than its counterparts at the onset of Wenckebach periods observed. Its cycle is also much shorter than the other pauses. it is, therefore, a junctional escape beat.

The AV conduction is quite prolonged (up to 0.48”) at a fast sinus rate, making the P waves “jump” over the T wave to activate the ventricles. The computer interpreted the multiple humps and the variable rate as atrial fibrillation.